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    Okay, so my textbook tells me that nicotine reduces the diameter of arterioles. This increases the resistant for the blood to flow. So, blood supply to the hands and feet decreases. But would, a smaller diameter increase pressure? Wouldn't an increase in pressure lead to an increase in blood supply? What am I missing?
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    What you said does make sense: however, you have to think about all the other arterioles in the body going other places. If it's harder for the blood to flow through one route, it will find another way, hence the lowered supply.
    Also, increased pressure doesn't increase the amount of blood going through, it's the same amount of blood just sped up a little due to the increased pressure. Does that make sense?
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    (Original post by Arcade22)
    What you said does make sense: however, you have to think about all the other arterioles in the body going other places. If it's harder for the blood to flow through one route, it will find another way, hence the lowered supply.
    Also, increased pressure doesn't increase the amount of blood going through, it's the same amount of blood just sped up a little due to the increased pressure. Does that make sense?
    So, when arterioles constrict, there is an increase in resistance which then causes the route of the blood to change. Okay, if that's the case, would that mean that all the arterioles doesn't constrict simultaneously? Let's say, just the arterioles at extremities?
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    (Original post by Grizzelex)
    So, when arterioles constrict, there is an increase in resistance which then causes the route of the blood to change. Okay, if that's the case, would that mean that all the arterioles doesn't constrict simultaneously? Let's say, just the arterioles at extremities?
    Sorry my bad yeah you need to specify extremities because if all arterioles constructed at the same time, we would be in big trouble
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    (Original post by Grizzelex)
    Okay, so my textbook tells me that nicotine reduces the diameter of arterioles. This increases the resistant for the blood to flow. So, blood supply to the hands and feet decreases. But would, a smaller diameter increase pressure? Wouldn't an increase in pressure lead to an increase in blood supply? What am I missing?
    Yes, increasing the resistance will decrease blood flow. And yes, vasoconstriction also increases the blood pressure within the arterioles which will partially offset the decrease in flow, however, the increase in pressure is not enough to overcome the increase in resistance and increase blood flow - so overall, blood flow goes down. Also, nicotine causes global vasoconstriction (i.e. vasoconstriction of arterioles all over the body), so there are no other 'routes' for the blood to go.
 
 
 
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